In wellbore drilling for the oil and gas industry, a drill bit may be mounted on the end of a drill string and rotated to break up a geologic formation. The drill bit may be rotated by turning the entire drill string, e.g., with a top drive at surface location, and/or the drill bit may be rotated using downhole equipment, such as a mud motor mounted within the drill string. When drilling, a drilling fluid is pumped through the drill string and discharged from the drill bit to remove cuttings and debris. The mud motor, if present in the drill string, may be selectively powered using the circulating drilling fluid.
One common type of drill bit is a “fixed cutter” bit, wherein cutters (also referred to as cutter elements, cutting elements, or inserts) are secured to a bit body at fixed positions. The bit body may be formed from a high strength material, such as tungsten carbide, steel, or a composite/matrix material, and the cutters may include a substrate or support stud made of a carbide (e.g., tungsten carbide), and an ultra-hard cutting surface layer or “table” made of a polycrystalline diamond material or a polycrystalline boron nitride material deposited onto or otherwise bonded to the substrate. Such cutters are commonly referred to as polycrystalline diamond compact (“PDC”) cutters.
Some cutters are strategically positioned along leading edges of blades defined on the bit body such that the cutters engage the formation during drilling. In use, high forces are exerted on the cutters, and over time, a working surface or cutting edge of each cutter eventually wears down or fails. The cutting edge of a fixed cutter may be continuously exposed to the formation, while an exposed surface of a rolling element may be successively exposed to the formation and withdrawn from the formation as it rotates on the drill bit. In some instances, rolling elements may provide depth of cut control to the fixed cutters.